Arithmetical frame



NITED STATES PATENT O FICE.

FREDERICK B. GINN, OF OAKLAND, CALIFORNIA.

'ARITHM ETICAL FRAM E.

SPECIFICATION forming part of Letters Patent No. 236,320, dated January4, 1881.

Application filed October 5, 1880. (No model.)

To all whom it may concern:

Be it known that I, FREDERICK B. GINN, a citizen of the United States,resident at Oakland, in the county of Alameda and State of California,have invented certain new and useful Im provements in Arithmeti-calFrames; and 1 do hereby declare the following to be a full, clear, andexact description of the invention, such as will enable others skilledin the art to which it appertains to'make and use the same, referencebeing had to the accompanying drawing, and to letters or figures ofreference marked thereon, which form a part of this specification.

This invention relates to arith metical frames for school, class, andprivate practice; and it consists in the improved features ofconstruction and combination hereinafter fully described, andparticularly pointed out in the claim.

The drawing represents a plan view of the device partly broken away.

Referring by letter to the accompanying drawing, A designates the frameof the machine, having a closed back, open front, and grooves B B at thesides, between the mat O and the back D, for the reception of the endsof the sliding slips E. The length of the sliding slips E is less thanthe width of the frame A at the grooves BB, in order that the slips maybe moved tothe right and left in the grooves. The slips E are in thisinstance provided each with nine figures, and eighteen of the strips areplaced in the frame. This size is intended for private use, and is madeof wood or paper. For school use the frame is made larger and thefigures on the slips of such size that they may be seen from any part ofthe room.

When the strips are all pushed to the lefthand side of the frame thenine columns of eighteen figures each are in their normal position. Bysliding any one of the strips to the right the combination will bechanged; and it is obvious that when each slip is moved the combinationwill be changed, so that a great variety of combinations are given forpractice in adding, and no time is lost in effecting the changes.

The advantages of the machine are plain. The device is quite simple, isinexpensive, and is of great benefit in aiding individuals as well asclasses to become proficient in adding.

It is obvious that any number of sliding slips with any number offigures upon each may be used without departing from the spirit of myinvention.

I am aware that an arithmetical frame provided with slats having numbersor figures on their opposite faces and arranged to be revolved or turnedover in a frame to change the combinations in the columns is not new, asthe same may be seen in Patent No. 43,545, July 12, 1864., and no claimto said construction is made-herein.

Having thus fully described my invention, what I claim as new, anddesire to secure by Letters Patent of the United States, is-- As animprovement in arithmetical frames, the frame A, having the closed back,open front, and grooves B B at the sides, between the mat O and back D,in combination with the series of figured or numbered sliding strips E,constructed and operating substantially as and for the purposes setforth. 4

In testimony whereof I affix my signature in presence of two witnesses.

FREDERICK B. GINN.

Witnesses:

ANDREW RYDER, M. P. KAY.

